SNPwatch: Genetic Variation In Tumor Suppressor May Predict Worse Outcome for African American Colorectal Cancer Patients

SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.

Colorectal cancer is the third most commonly diagnosed cancer in the U.S., and the third leading cause of cancer death.  In 2008 close to 50,000 people succumbed to the disease.

But not all groups are affected equally.  An American Cancer Society study found that colorectal cancer incidence rates are more than 20% higher for African Americans than Caucasians. Death rates from the disease are 45% higher.

Lifestyle factors, access to healthcare and cultural differences have all been proposed as reasons to explain the racial disparities in colorectal cancer survival. But new research from the University of Alabama, published today in the journal Clinical Cancer Research, shows that for some African Americans, genetics may play a part too.

Researchers analyzed 373 colorectal tumors – 137 taken from African Americans and 236 taken from non-Hispanic Caucasians.  They found that African American patients with two Gs at rs1042522 in the p53 gene were 2.15 times more likely to die of colorectal cancer than those with one or no copies of a G at this SNP.  In Caucasians there was no association between survival and rs1042522.

Seventeen percent of African American patients had two Gs, while only 7% of Caucasian patients did.

(23andMe customers can check their data for rs1042522 using the Browse Raw Data feature.)

The p53 gene encodes a tumor suppressor protein that protects against cancer, in part, by telling damaged cells to self-destruct instead of turning into tumors.  Mutations in the p53 gene that disrupt its function are a common feature of many cancers. (These mutations are distinct from the rs1042522 variation.)

Although the findings will need to be replicated in larger studies, the study’s authors suggest that rs1042522 might be a race-specific prognostic marker for African American patients with colorectal cancers and that someday analysis of this SNP might aid in designing optimal treatment regimens.


  • Michael Lacy

    I have CG at tp53..does that mean I have a mutation? Why are. 2 C’s better than one?

    • http://23andme.com Shwu

      Hi Michael,

      According to the study described in this post, only having the GG genotype at rs1042522 was associated with worse outcome for African American patients with colorectal cancer. If you are CG at rs1042522, this is associated with a typical outcome in African Americans who have colorectal cancer. Having two Cs is not necessarily preferable, but these researchers observed that those who had two Gs at that variant fared worse than those with one or no Gs. The G version of rs1042522 is actually fairly common in African Americans, but somewhat less common in Caucasians.

      Hope this helps clarify things!

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